My step father is piling up medical bills from his condition and will be needing possible nursing care along with credit debt, he never adopted legal ,he married my mother, my question is am I legal liable for his medical bills n possible nursing care, I know now not responsible his credit debt n medical bills, but being told by social worker I am for his long term care

I'm not sure if you would be responsible even if you were his natural child. But I'm pretty sure you are not responsible for a step father. Ask the social worker to show you what laws or rules require you to be responsible.

Any question on law needs to include your general locale as laws vary by area. Its impossible for us to confirm the social worker without knowing where you are located.

You are NOT responsible legally in the US, so where are you?

I'm wondering if you misunderstood based on facts you haven't told us? If you are living in his house, the state can take it and sell it to pay for any nursing care he can't afford. They can evict you if it's his name on the deed. Any changes made to the deed in the last 5 years don't count.

IF you are in the US.